[The effect of nitric oxide synthase inhibitor on reperfusion injury to the brain under hypothermic circulatory arrest].

The effect of nitric oxide synthase inhibitor-NG-nitro-L-argine methyl ester (L-NAME)-on reperfusion injury of the brain under deep hypothermic circulatory arrest was experimentally investigated in sixteen piglets weighing about 30 kg. Cardiopulmonary bypass was established and animals were cooled to a brain temperature of 20 degrees C and circulatory arrest was performed for 60 minutes followed by reperfusion of 120 minutes. The value of nitric oxide (NO) within the brain was measured with a needle electrode which was inserted into the brain. In the treatment group L-NAME was administered with a intravenous injection of 1.5 mg/kg at the beginning of the reperfusion followed by a 60-minute continuous venous infusion of 1.5 mg/kg/hour. In the control group the value of NO after 120 minutes reperfusion increased significantly compared with pre-circulatory arrest, but in the treatment group it did not. There was significant difference between the groups regarding the NO value after 120 minutes reperfusion. Blood pressure after 120 minutes reperfusion in the treatment group was a little higher than the control group, but there was no significant difference between the groups regarding cerebral blood flow, excess lactate and cerebral tissue water content. However, recovery of SEP after 120 minutes reperfusion was detected in all 8 cases of the treatment group, but only in one of the control group (p < 0.001). This data suggests that L-NAME protects the brain against the reperfusion injury under deep hypothermic circulatory arrest.